The present invention relates to a clamping spring for a spring terminal, having a fixed leg and an angular spring leg located resiliently on the fixed leg. Such clamping springs, which are also referred to as xe2x80x9ccage springsxe2x80x9d, are used in screwless terminals that are known, for example, from European Patent 0 303 818 B1.
In the technical field of terminals and connectors, as in many technical fields, there is a trend toward miniaturization of components. That means that there is always only limited installation space available inside a terminal for the clamping spring. That limited installation space conflicts with the necessity of providing larger clamping springs for contacting conductors having large conductor cross sections. In other words, the installation space for the clamping spring in the terminal is the bottleneck factor for the maximum connectable conductor cross section.
It is accordingly an object of the invention to provide a clamping spring for a spring terminal which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type in such a way that conductors with large conductor cross sections can also be clamped in the spring.
With the foregoing and other objects in view there is provided, in accordance with the invention, a clamping spring for a spring terminal, comprising a fixed leg, an angular spring leg disposed resiliently on the fixed leg and an auxiliary spring leg disposed resiliently on the fixed leg. The auxiliary spring leg has a spring force acting on the spring leg. The clamping spring is formed of one bent piece.
The invention is based on the fundamental concept of increasing the effective spring force of the clamping spring in order for it to be possible, as a result, to exert a greater clamping force on the conductor. Due to this greater clamping force, a comparatively greater conductor cross section can be clamped in a clamping spring of the same size and the same bending stress. Conversely, this means a saving in terms of the size of the clamping spring. Therefore, in relation to conventional clamping springs, the clamping spring according to the invention has not only a spring leg which serves for clamping the conductor and is located resiliently on a fixed leg, but also an additional auxiliary spring leg which increases, and ideally virtually doubles, the sum of the spring forces exerted by the clamping spring. This structure of a bent component, preferably a one-piece spring-steel bent component is simple in terms of manufacture and thus advantageous and contributes to reducing production costs.
The following developments of the invention in some cases are advantageous and in some cases are inventive in themselves as well.
In accordance with another feature of the invention, there is provided a spring excursion limiter formed on the auxiliary spring leg. The spring excursion limiter prevents over-pressing of the clamping spring during the connection operation. This is relevant in terms of safety, because over-pressing of the clamping spring during contacting may go unnoticed by the operator. In that case, the contact between the conductor and the clamping spring may initially appear to be made but subsequently fail, without the faulty contacting being identifiable from outside as the reason for the failure.
In accordance with a further feature of the invention, the fixed leg and the spring leg surround a spring interior, and the auxiliary spring leg is disposed in the spring interior. Accordingly, the invention makes use of the fact that, in known clamping springs, the fixed leg and the spring leg surround a spring interior which, in the final mounted state of the clamping spring, lies idle in an effectively wasted manner. According to the invention, this spring interior that conventionally lies idle in an effectively wasted manner is used as the installation space for the auxiliary spring leg. In this way, the auxiliary spring leg can be accommodated without any difficulties while retaining exactly the same installation space as for the clamping spring according to the state of the art.
In accordance with an added feature of the invention, the spring leg on one hand and the auxiliary spring leg on the other hand are formed on two different free ends of the fixed leg. Therefore, in the event of failure of one of the two spring legs, the other spring leg in each case can nevertheless completely retain its ability to function.
In a first preferred embodiment of the invention, the auxiliary spring leg has a geometry adapted to the geometry of the clamping spring. Therefore, in accordance with an additional feature of the invention, the auxiliary spring leg is substantially V-shaped and has a spring auxiliary bar lying snugly next to a partial region of the spring leg like a skeleton and a base auxiliary bar disposed at the fixed leg. In accordance with yet another feature of the invention, there is provided a bulge bent out toward the spring leg and disposed between the fixed leg and the base auxiliary bar, as a spring excursion limiter.
Another embodiment of the invention is regarded as advantageous in particular with regard to its spring characteristics. Therefore, in accordance with yet a further feature of the invention, the auxiliary spring leg has a free end facing away from the fixed leg and bearing against the spring leg, and the auxiliary spring leg and the spring leg move in opposite directions. In accordance with a concomitant feature of the invention, the free end of the auxiliary spring leg bears against the spring leg as a slide guide and has a rounding, and the free end has a bent-off region forming an extension of the rounding acting as a spring excursion limiter.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a clamping spring, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.